Three-Choice Chlordiazepoxide, Saline, and Pentylenetetrazole Discrimination in Rats: Cross-Generalization Between Drug and (Olfactory) Alarm Substance Stimuli

Sprague-Dawley rats ( Rattus norvegicus ) were trained to discriminate between 3 mg/kg chlordiazepoxide (CDP), saline (SAL), and 15 mg/kg pentylenetetrazole (PTZ) in an operant lever-press task. Animals were tested with various doses of CDP and PTZ that demonstrated pharmacological specificity of the stimulus control. Tests were conducted after SAL pretreatments with alarm substance pheromones that were deposited by 2 strains of donor rats (Sprague-Dawley and Wistar) exposed to footshock presentations in the operant chambers just before the discrimination test sessions. In addition, a compound stimulus from these same 2 donor strains of rats was tested that was composed of the alarm substance pheromone deposited by footshock presentation to the donor rats plus 15 min preexposure to the presence of a sanguinous stimulus from similarly treated donor rats. Although the anxiogenic state induced by the alarm substance presentation alone engendered partial generalization to the PTZ training stimulus, exclusive PTZ-appropriate responding was engendered by the compound stimulus condition. The anxiogenic state that engendered PTZ-appropriate responding was limited to the within-strain tests with Sprague-Dawley donor rats. These data suggest that an ethologically relevant, strain-dependent pheromone can induce subjective states in rats similar to a 15 mg/kg PTZ training cue.